嵌入水印对音频信号波形的影响受到的关注不多。分析得出改变采样序列离散余弦变换（Discrete Co-sine Transform ，DCT ）域某个交流系数时，逆DCT后幅值变化服从余弦曲线，改变离散小波变换（Discrete Wavelet Trans-form ，DWT ）域某个近似系数时，重构后采样序列幅值变化呈现为所选小波的尺度函数。并对在DWT-DCT混合域嵌入水印做了讨论。通过推导和实验，得到采样点的改变量与DCT域低频系数的改变量、DWT域近似系数的改变量及混合域低频系数的改变量成线性关系。所得结论有助于发现嵌入算法带给采样点序列的不连续变化而使含水印音频产生可听噪声，也有助于提高水印的嵌入效率。%The distortion of audio signal associated with watermarking has received little attention .We have obtained some distortion laws in this paper .When a certain alternative coefficient is modified in DCT (Discrete Cosine Transform ) domain ,the law of audio amplitude distortion meets the cosine curve after inverse DCT .For the DWT (Discrete Wavelet Transform ) domain audio watermarking ,the distortion of audio signal shows the shape of scaling function after inverse DWT if a certain approximation coeffi-cient in DWT domain is justified .Furthermore ,analysis on embedding watermark in DWT-DCT domain is performed .By derivations and experiments ,we draw the conclusions that the relationships between the variation of sample value and that of the low frequency coefficients in DCT ,that of the approximation coefficient in DWT ,and that of the low frequency coefficient in hybrid domain ,are linear respectively .Our conclusions are helpful to find the discontinuities due to embedding watermark ,which may cause audible noise ,and improve the efficiency of embedding watermark .
展开▼
